Re: QMX 10-20m LPF0 problem?
Hi Jo! My QMX high band had initially also around 3W output which I found a bit meagre. I tried LPF1 and then I had too much output to feel safe (I think it was 6.7W). I went back to LPF0 and fiddled a bit with compressing and separating the windings of the toroids and got a bit more power. I found that separating the winding was the way to go and then I realized that maybe I should remove one turn on each toroid. I did so and noted that this was worse. Back to the original numbers of turns and a bit more fiddling, and after a while I was able to get 3.9W which I found decent. So I stopped. In the real world the difference between 3.0W and 3.9W is very small but this is a hobby where you kill time in a pleasant way. Try to compress and separate the windings. I don't think there is anything wrong with your setup other than that the tolerances of your components may play you a game.
Another thing I did was to replace the CB-band with 30M and run it through LPF0. I got 3W output on 30M and the current consumption looks fine. I was happy about that. I don't know how much of unwanted overtones that passes through the filter, and right now I don't really care. I may check that later some time. Maybe someone knows how good the LPF0 cut for 20M works on 30M...? And if there are other implications to ponder about when adding 30M like that.
Good luck, Jo!
Anders
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I've been catching up on my YouTube videos and just published a September POTA activation using my QMX and a modified PAC-12 antenna. I also used a KN4YB bug, which was a little scratchy at first. Not my best bug work, but the rig performed fantastically with one DX contact on an otherwise difficult propagation day. The QSB was very deep!
If you are learning CW, be sure to toggle the CC button to see the decoded CW.
--
72/73 de Steve, K9NUD
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Re: QMX RX dead after testing TX with dummy load - can FST3253 replace CBT3253?
Ronan,
The mod addresses a problem that is exhibited by Rev 2 boards only. So far, Rev 1 and QDX appear to escape the problem.?
JZ
Very informative post, Bev. Thanks.
Just for clarity, does this mod only apply to the Rev 2 PCB? I suspect it does but I thought I'd double check as I have a Rev 1 rig here.
Cheers,
Ronan
MM0IVR?
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Re: QMX RX dead after testing TX with dummy load - can FST3253 replace CBT3253?
Very informative post, Bev. Thanks.
Just for clarity, does this mod only apply to the Rev 2 PCB? I suspect it does but I thought I'd double check as I have a Rev 1 rig here.
Cheers,
Ronan
MM0IVR?
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Re: QMX RX dead after testing TX with dummy load - can FST3253 replace CBT3253?
Bev,
Thanks for posting the photos and sharing your experience. Hopefully you will have made things much easier for others.
Wishing you New Year's 72/73 and much success with your QMX.
JZ KJ4A?
JZ, you are so right but I feel so embarrased. You will understand when you see the picture. This is the whole picture. Q508 is to be found "north of" the unlucky IC402 band switch (here already replaced by FST3253). C508 is on the left and L509 is on the right of Q508 (BSS123, here replaced by 2N7002 after I accidentally tore off Q508 drain lead together with the whole PCB trace up to C509, here already replaced by wire). Detail: C508 "south" and L509 "north" connected by 1N4148 oriented C-A. Please continue to read my important note below. BEFORE soldering the diode, you ABSOLUTELY must prepare its leads, i.e. form the length and shape of the leads exactly to fit the anticipated final position of the diode (including height above Q508 and the PCB), cover the leads with a very thin but solid layer of solder using flux. Only after you have everything ready, solder the leads to C508 ("south") and L509 ("north"). IF YOU ATTEMPT to "correct" position of the diode AFTER it's soldered, you will inevitably tear off the thin tinned surface of the respective SMD component, possibly disconnecting the solder from the respective end, and also TEAR OFF the PCB trace it is soldered to. Especially make sure the diode will not protrude too high above Q508 because when you put the whole set into the standard enclosure provided by QRP Labs, it might press the diode if it protrudes too much, causing leverage force onto both the C508 and L509 and that could cause?damage or destruction of C508, as well as L509, and/or the connected PCB traces. To fix the nearby Q508 might be relatively easy but fixing the two other tiny SMD components (I think one is size 0603 and the other one 0804) would be really difficult task. I was very lucky that the trace from Q508 drain to C509 was straight at the same surface layer and without through-holes. You don't deserve to repeat my stupid errors. :-D 73 Bev On Tue, Jan 2, 2024 at 01:12 AM, John Z wrote:
Bev, post a picture of the diode mod. It will be useful to all.
?
JZ
SOLVED
I replaced the smoked CBT3253 by an FST3253 from my home stock, everything works.
Then I was looking for the "safety diode" installation mentioned here:?/g/QRPLabs/message/115735
The "right end" of C508 was easy to find, it is the one not connected to ground, can be checked by a multimeter for continuity. Then it appears from the PCB sketch in assembly manual that the place for diode anode is the "opposite" end of L503. So if you look at C508 and cathode of the diode should be connected to the "south end" of C508, the anode the has to be soldered to "north end" of L503. The distance is just about far enough to acommodate through-hole 1N4148 with leads bent? tightly. Leave the bent leads of 1N4148 just long enough to keep the diode tightly above Q508. Before placing the diode to PCB, make sure to have ends of leads tinned by fresh solder, then solder diode leads to C508 and L503, adding a micro droplet of solder if necessary.
It took me several hours to figure out how to solder the diode, especially with regard to L503. In the process I mechanically damaged Q508 (BSS123) but luckily I had a few spare 2N7002's (exact equivalent) so I was able to finish everything without having to wait till morning when they open electronic parts shop :)
I hope the diode will finally prevent IC402 from further failure for good because my QMX produces 6 watts on some bands. Since I finished the kit, I had to do two repairs and one mod and I think now I deserve enjoying some fun with the QMX. It's a beautiful and effective radio, I have never had such satisfaction working other QRP rigs (NorCal 2030, KX3).
73 Jindra "Bev" OK4RM
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Hello,
is there a known setup for RTTY using fldigi and VARA setup?
I have had success with JS8Call, although TX signal required unusually high level setting (around -1? to -2 dB, while with TS-590S or G90 it was somewhere in the range -17 dB or lower) - but I suppose the higher the input level the lower the risk of including unwanted noise in the transmitted signal).
However, with VARA and FLdigi I had no TX output. FLdigi uses flrig to control the transceiver (which is perfectly OK), when I switch to TX it seems QMX is switched, too (sound in headphones disappear) but there is no output even when I set transmit level to 0 dB.
Is there anything else I need to pay attention to?
73 Jindra OK4RM
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QMX repair service in Europe?
Hello all a happy 2024 to all fo you
after reading the assembly manual in holidays I'd soldering the QMX in a few days followed all instructions carefully.?
after inspection I'd power up QMX with 7V and nada, reading troubleshooting guide changed the USB-C to USB-A I could power up QMX, I was sooo happy!
did some RX tests on a Magloop Antenna and TX on a dummyload (SWR on Magloop was to bd for TX) successfully
Suddently smoke and the usual ugly smell?
It seems there was a short just. picture shows clearly the cause.
My question is, is there a QMX repair service? in Europe (of courese I will pay for it?)
?
Picture of the damage: https://1drv.ms/i/s!AkLfGE3tdajgltdJa0PhnAdSrbaSkw?e=O6WdBd
best 73 Remo es HB9SHD?
?
?
?
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Re: QMX RX dead after testing TX with dummy load - can FST3253 replace CBT3253?
JZ, you are so right but I feel so embarrased. You will understand when you see the picture.
This is the whole picture. Q508 is to be found "north of" the unlucky IC402 band switch (here already replaced by FST3253). C508 is on the left and L509 is on the right of Q508 (BSS123, here replaced by 2N7002 after I accidentally tore off Q508 drain lead together with the whole PCB trace up to C509, here already replaced by wire).
Detail: C508 "south" and L509 "north" connected by 1N4148 oriented C-A. Please continue to read my important note below.
BEFORE soldering the diode, you ABSOLUTELY must prepare its leads, i.e. form the length and shape of the leads exactly to fit the anticipated final position of the diode (including height above Q508 and the PCB), cover the leads with a very thin but solid layer of solder using flux. Only after you have everything ready, solder the leads to C508 ("south") and L509 ("north").
IF YOU ATTEMPT to "correct" position of the diode AFTER it's soldered, you will inevitably tear off the thin tinned surface of the respective SMD component, possibly disconnecting the solder from the respective end, and also TEAR OFF the PCB trace it is soldered to. Especially make sure the diode will not protrude too high above Q508 because when you put the whole set into the standard enclosure provided by QRP Labs, it might press the diode if it protrudes too much, causing leverage force onto both the C508 and L509 and that could cause?damage or destruction of C508, as well as L509, and/or the connected PCB traces. To fix the nearby Q508 might be relatively easy but fixing the two other tiny SMD components (I think one is size 0603 and the other one 0804) would be really difficult task. I was very lucky that the trace from Q508 drain to C509 was straight at the same surface layer and without through-holes. You don't deserve to repeat my stupid errors. :-D
73 Bev
toggle quoted message
Show quoted text
On Tue, Jan 2, 2024 at 01:12 AM, John Z wrote:
Bev, post a picture of the diode mod. It will be useful to all.
?
JZ
SOLVED
I replaced the smoked CBT3253 by an FST3253 from my home stock, everything works.
Then I was looking for the "safety diode" installation mentioned here:?/g/QRPLabs/message/115735
The "right end" of C508 was easy to find, it is the one not connected to ground, can be checked by a multimeter for continuity. Then it appears from the PCB sketch in assembly manual that the place for diode anode is the "opposite" end of L503. So if you look at C508 and cathode of the diode should be connected to the "south end" of C508, the anode the has to be soldered to "north end" of L503. The distance is just about far enough to acommodate through-hole 1N4148 with leads bent? tightly. Leave the bent leads of 1N4148 just long enough to keep the diode tightly above Q508. Before placing the diode to PCB, make sure to have ends of leads tinned by fresh solder, then solder diode leads to C508 and L503, adding a micro droplet of solder if necessary.
It took me several hours to figure out how to solder the diode, especially with regard to L503. In the process I mechanically damaged Q508 (BSS123) but luckily I had a few spare 2N7002's (exact equivalent) so I was able to finish everything without having to wait till morning when they open electronic parts shop :)
I hope the diode will finally prevent IC402 from further failure for good because my QMX produces 6 watts on some bands. Since I finished the kit, I had to do two repairs and one mod and I think now I deserve enjoying some fun with the QMX. It's a beautiful and effective radio, I have never had such satisfaction working other QRP rigs (NorCal 2030, KX3).
73 Jindra "Bev" OK4RM
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Re: QMX HW Diagnostics: No TX?
Hans, thanks! I will remember that.
JZ
Hi JZ
An important note about this... You are right that there's a setting to keep the PA modulator high during RX. However: when the diagnostics screen is open, the PA modulator voltage is always low on RX, regardless of the normal setting. Therefore if one sees a high PA voltage in the diagnostics screen when not keying the transmitter, which will be coloured red, it does always indicate an issue with the PA modulator.?
73 Hans G0UPL
Todd,
In FW rev 1_00_011 a feature was added to enable the TX voltage (in RX)? to be set well above zero. (3a: Mod high in RX).
?Leaving it at zero was creating undesired capacitive loading of the RX path and potential diode-induced IMD as well. Restoring some voltage at the drains of the BS170s solves that problem.
Check to see if you have that option enabled on your QMX.
If not, and if you still have voltage showing in RX, there may be a hardware problem with the modulator circuit.
JZ KJ4A?
On Mon, Jan 1, 2024, 3:11?PM Todd W2TEF < w2tef@...> wrote: Hmmm... my diodes look like they're correctly oriented. I can't locate any evidence of damage or shorts to any components, particularly around the toroids and inductors. I'm absolutely willing to take another swing at the toroids if they're suspect. But I feel like the diagnostic screen gave me a clear pointer toward a problem:
 
When transmitting, the voltage is at 10.1v (and output of 0 watts!). The operation manual states (p. 73, v.014):
Additionally, the PA voltage is measured,
after the RF envelope shaping (amplitude modulation). In transmit, this should be a little less than
the supply voltage measurement. In receive, it should be near to zero volts. The PA voltage is
coloured green or red depending on whether it is within a reasonable operating range or not."
But in receive, it's still at 10.1v. I see other images in the forum showing that value at, e.g., 0.6v at receive.
Where is this reading being taken? Perhaps I need to look "near" there in the circuit for a nicked wire or a solder whisker??
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Re: QMX HW Diagnostics: No TX?
Hi JZ
An important note about this... You are right that there's a setting to keep the PA modulator high during RX. However: when the diagnostics screen is open, the PA modulator voltage is always low on RX, regardless of the normal setting. Therefore if one sees a high PA voltage in the diagnostics screen when not keying the transmitter, which will be coloured red, it does always indicate an issue with the PA modulator.?
73 Hans G0UPL
Todd,
In FW rev 1_00_011 a feature was added to enable the TX voltage (in RX)? to be set well above zero. (3a: Mod high in RX).
?Leaving it at zero was creating undesired capacitive loading of the RX path and potential diode-induced IMD as well. Restoring some voltage at the drains of the BS170s solves that problem.
Check to see if you have that option enabled on your QMX.
If not, and if you still have voltage showing in RX, there may be a hardware problem with the modulator circuit.
JZ KJ4A?
On Mon, Jan 1, 2024, 3:11?PM Todd W2TEF < w2tef@...> wrote: Hmmm... my diodes look like they're correctly oriented. I can't locate any evidence of damage or shorts to any components, particularly around the toroids and inductors. I'm absolutely willing to take another swing at the toroids if they're suspect. But I feel like the diagnostic screen gave me a clear pointer toward a problem:
When transmitting, the voltage is at 10.1v (and output of 0 watts!). The operation manual states (p. 73, v.014):
Additionally, the PA voltage is measured,
after the RF envelope shaping (amplitude modulation). In transmit, this should be a little less than
the supply voltage measurement. In receive, it should be near to zero volts. The PA voltage is
coloured green or red depending on whether it is within a reasonable operating range or not."
But in receive, it's still at 10.1v. I see other images in the forum showing that value at, e.g., 0.6v at receive.
Where is this reading being taken? Perhaps I need to look "near" there in the circuit for a nicked wire or a solder whisker??
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Re: QMX HW Diagnostics: No TX?
Todd, before you pull Q507, look carefully at everything that connects to its gate. A short to ground or near-ground at that point can also corrupt the measured resistance at R507 and cause the circuit to malfunction even with a good transistor.
JZ
Todd,
Since C507 sits right on the 12V supply, don't expect to see a high impedance there. R507 is a different matter. A resistance of 500 ohms there indicates that Q507, the AOD403, has been damaged. I think you are getting close to a fix now.
73 JZ KJ4A?
On Mon, Jan 1, 2024, 6:44?PM Todd W2TEF < w2tef@...> wrote: Thank you for the pointers, John!
I found the setting, and tried toggling it. There was no change in the diagnostic behavior (still showing 10.v on receive or transmit).
I started examining the schematics: was delighted to find that not only is the transmitter contained on a single page, but that all the parts are numbered 5xx to show they belong to the transmitter! So I went hunting 500-series parts to check for clean solder connections/separations. (Those spacing tolerances are super-tight!)
I found & removed a solder ball. Then I hit the jackpot: a testable short between T501 and R506. I cleaned that up and my transmitter voltage dropped to 5.1v. Brilliant!
Though the voltage stays at 5.1v on transmit. Not so great.
I went through tracing other connections in the transmitter, touching up a few of them. Now my voltage in the transmitter is 5.8v (too high), receive or transmit.
I wonder if running it with that short destroyed something else up the line. I'm guessing the BS170's are in decent shape because I can still run SWR sweeps (and they look better now than before: more consistent). I'll continue tracing through the transmitter to see what else I might turn up. Mainly checking for solid connections (continuity).?
I did notice that R507 only seems to present 50ohms of resistance instead of its designated 5.6k. Though since it is in a circuit, perhaps there are other paths I'm measuring when I put my probes on the resistor. Likewise, C507 only seems to present 500ohms of resistance between its ungrounded side and the ground. Again, there may be other paths I do not discern. I'm looking at Q507.
There are some threads that might pertain to Q507. I need to read them tomorrow and see what I can learn about testing it.
Thanks again for pointing me in the right direction!
?
Todd W2TEF
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Re: QMX RX dead after testing TX with dummy load - can FST3253 replace CBT3253?
I've been following this thread and added the diode.
I thought I would include the image of what I did, and sounds like the same placement.
73 and Happy New Year!
Chris?
Bev, post a picture of the diode mod. It will be useful to all.
JZ
SOLVED
I replaced the smoked CBT3253 by an FST3253 from my home stock, everything works.
Then I was looking for the "safety diode" installation mentioned here:?/g/QRPLabs/message/115735
The "right end" of C508 was easy to find, it is the one not connected to ground, can be checked by a multimeter for continuity. Then it appears from the PCB sketch in assembly manual that the place for diode anode is the "opposite" end of L503. So if you look at C508 and cathode of the diode should be connected to the "south end" of C508, the anode the has to be soldered to "north end" of L503. The distance is just about far enough to acommodate through-hole 1N4148 with leads bent? tightly. Leave the bent leads of 1N4148 just long enough to keep the diode tightly above Q508. Before placing the diode to PCB, make sure to have ends of leads tinned by fresh solder, then solder diode leads to C508 and L503, adding a micro droplet of solder if necessary.
It took me several hours to figure out how to solder the diode, especially with regard to L503. In the process I mechanically damaged Q508 (BSS123) but luckily I had a few spare 2N7002's (exact equivalent) so I was able to finish everything without having to wait till morning when they open electronic parts shop :)
I hope the diode will finally prevent IC402 from further failure for good because my QMX produces 6 watts on some bands. Since I finished the kit, I had to do two repairs and one mod and I think now I deserve enjoying some fun with the QMX. It's a beautiful and effective radio, I have never had such satisfaction working other QRP rigs (NorCal 2030, KX3).
73 Jindra "Bev" OK4RM
|
Re: QMX HW Diagnostics: No TX?
Todd,
Since C507 sits right on the 12V supply, don't expect to see a high impedance there. R507 is a different matter. A resistance of 500 ohms there indicates that Q507, the AOD403, has been damaged. I think you are getting close to a fix now.
73 JZ KJ4A?
On Mon, Jan 1, 2024, 6:44?PM Todd W2TEF < w2tef@...> wrote: Thank you for the pointers, John!
I found the setting, and tried toggling it. There was no change in the diagnostic behavior (still showing 10.v on receive or transmit).
I started examining the schematics: was delighted to find that not only is the transmitter contained on a single page, but that all the parts are numbered 5xx to show they belong to the transmitter! So I went hunting 500-series parts to check for clean solder connections/separations. (Those spacing tolerances are super-tight!)
I found & removed a solder ball. Then I hit the jackpot: a testable short between T501 and R506. I cleaned that up and my transmitter voltage dropped to 5.1v. Brilliant!
Though the voltage stays at 5.1v on transmit. Not so great.
I went through tracing other connections in the transmitter, touching up a few of them. Now my voltage in the transmitter is 5.8v (too high), receive or transmit.
I wonder if running it with that short destroyed something else up the line. I'm guessing the BS170's are in decent shape because I can still run SWR sweeps (and they look better now than before: more consistent). I'll continue tracing through the transmitter to see what else I might turn up. Mainly checking for solid connections (continuity).?
I did notice that R507 only seems to present 50ohms of resistance instead of its designated 5.6k. Though since it is in a circuit, perhaps there are other paths I'm measuring when I put my probes on the resistor. Likewise, C507 only seems to present 500ohms of resistance between its ungrounded side and the ground. Again, there may be other paths I do not discern. I'm looking at Q507.
There are some threads that might pertain to Q507. I need to read them tomorrow and see what I can learn about testing it.
Thanks again for pointing me in the right direction!
?
Todd W2TEF
|
Re: QMX HW Diagnostics: No TX?
Thank you for the pointers, John! I found the setting, and tried toggling it. There was no change in the diagnostic behavior (still showing 10.v on receive or transmit). I started examining the schematics: was delighted to find that not only is the transmitter contained on a single page, but that all the parts are numbered 5xx to show they belong to the transmitter! So I went hunting 500-series parts to check for clean solder connections/separations. (Those spacing tolerances are super-tight!) I found & removed a solder ball. Then I hit the jackpot: a testable short between T501 and R506. I cleaned that up and my transmitter voltage dropped to 5.1v. Brilliant! Though the voltage stays at 5.1v on transmit. Not so great. I went through tracing other connections in the transmitter, touching up a few of them. Now my voltage in the transmitter is 5.8v (too high), receive or transmit. I wonder if running it with that short destroyed something else up the line. I'm guessing the BS170's are in decent shape because I can still run SWR sweeps (and they look better now than before: more consistent). I'll continue tracing through the transmitter to see what else I might turn up. Mainly checking for solid connections (continuity).? I did notice that R507 only seems to present 50ohms of resistance instead of its designated 5.6k. Though since it is in a circuit, perhaps there are other paths I'm measuring when I put my probes on the resistor. Likewise, C507 only seems to present 500ohms of resistance between its ungrounded side and the ground. Again, there may be other paths I do not discern. I'm looking at Q507. There are some threads that might pertain to Q507. I need to read them tomorrow and see what I can learn about testing it. Thanks again for pointing me in the right direction! ? Todd W2TEF
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QDX Rev 5 High Band Internal Noise
Hi Y'all,
I have an issue with my 13 month old QDX. It just recently started doing it without me knowingly causing it. It is showing a bunch of vertical lines, 62.5 hz apart on the waterfall. There are stronger lines every 500 hz, but weaker ones at 62.5 hz the whole span of the waterfall. This is on all bands.
The sweeps all look normal and the rig still functions in Rx and Tx, but of course not as well as it should on Rx.
The screenshot below is with the dummy load connected after removing the antenna.
Best I can tell, it's not the environment being picked up since my low band QDX does not show any of this when hooked up to the same connections and band.
I have no idea where to go from here.?
Any and all suggestions and ideas gratefully welcomed. 73,
Cliff, AE5ZA
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Re: QMX RX dead after testing TX with dummy load - can FST3253 replace CBT3253?
Bev, post a picture of the diode mod. It will be useful to all.
JZ
SOLVED
I replaced the smoked CBT3253 by an FST3253 from my home stock, everything works.
Then I was looking for the "safety diode" installation mentioned here:?/g/QRPLabs/message/115735
The "right end" of C508 was easy to find, it is the one not connected to ground, can be checked by a multimeter for continuity. Then it appears from the PCB sketch in assembly manual that the place for diode anode is the "opposite" end of L503. So if you look at C508 and cathode of the diode should be connected to the "south end" of C508, the anode the has to be soldered to "north end" of L503. The distance is just about far enough to acommodate through-hole 1N4148 with leads bent? tightly. Leave the bent leads of 1N4148 just long enough to keep the diode tightly above Q508. Before placing the diode to PCB, make sure to have ends of leads tinned by fresh solder, then solder diode leads to C508 and L503, adding a micro droplet of solder if necessary.
It took me several hours to figure out how to solder the diode, especially with regard to L503. In the process I mechanically damaged Q508 (BSS123) but luckily I had a few spare 2N7002's (exact equivalent) so I was able to finish everything without having to wait till morning when they open electronic parts shop :)
I hope the diode will finally prevent IC402 from further failure for good because my QMX produces 6 watts on some bands. Since I finished the kit, I had to do two repairs and one mod and I think now I deserve enjoying some fun with the QMX. It's a beautiful and effective radio, I have never had such satisfaction working other QRP rigs (NorCal 2030, KX3).
73 Jindra "Bev" OK4RM
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Re: QMX RX dead after testing TX with dummy load - can FST3253 replace CBT3253?
SOLVED I replaced the smoked CBT3253 by an FST3253 from my home stock, everything works. Then I was looking for the "safety diode" installation mentioned here:? /g/QRPLabs/message/115735The "right end" of C508 was easy to find, it is the one not connected to ground, can be checked by a multimeter for continuity. Then it appears from the PCB sketch in assembly manual that the place for diode anode is the "opposite" end of L503. So if you look at C508 and cathode of the diode should be connected to the "south end" of C508, the anode the has to be soldered to "north end" of L503. The distance is just about far enough to acommodate through-hole 1N4148 with leads bent? tightly. Leave the bent leads of 1N4148 just long enough to keep the diode tightly above Q508. Before placing the diode to PCB, make sure to have ends of leads tinned by fresh solder, then solder diode leads to C508 and L503, adding a micro droplet of solder if necessary. It took me several hours to figure out how to solder the diode, especially with regard to L503. In the process I mechanically damaged Q508 (BSS123) but luckily I had a few spare 2N7002's (exact equivalent) so I was able to finish everything without having to wait till morning when they open electronic parts shop :) I hope the diode will finally prevent IC402 from further failure for good because my QMX produces 6 watts on some bands. Since I finished the kit, I had to do two repairs and one mod and I think now I deserve enjoying some fun with the QMX. It's a beautiful and effective radio, I have never had such satisfaction working other QRP rigs (NorCal 2030, KX3). 73 Jindra "Bev" OK4RM
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Re: QMX no Rx after a few days of operation
OK4RM,
I don't have a way to make/send you an image at the moment.?
My suggestion is to take an ohmmeter set to a low range and ground one lead. Probe the inductor with the other lead. One terminal should read close to zero. The other terminal will read the resistance of the inductor, small but not zero. That is the lead you want to connect to.
If you look at the image of the PCB layout in the QMX documentation, you should be able to confirm your selection by following the inductor ground connection.
73, JZ
hello could you pls indicate which end of L503 at the PCB is the right one?
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Re: QMX no Rx after a few days of operation
Hello Hans.?In your case, do you hear band noise or do you not have audio at all?
73, Juan LU9CYV
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K9NUD-Steve
Todd W2TEF
Juan